1. Field of the Invention
The present invention relates generally to cable clamps for electrical outlet boxes or the like, and in a more particular sense, relates to clamps of this type limited to the engagement of cables having a non-metallic insulating sheathing. In yet a more particular sense, the invention has reference to cable clamps of the character described that are formed entirely of a plastic material, preferably by an extrusion process.
2. Description of the Prior Art
Outlet or junction boxes, whether plastic or metallic, are formed with knock-outs that are selectively removable to permit the insertion of one or more electrical cables into the box.
It is required that the inserted cables be clamped securely. To this end, many cable clamps have been designed, intended to efficiently discharge this function while yet meeting any one or more of various other desirable purposes, such as low manufacturing cost and ease of use.
Heretofore, however, in the highly competitive field of outlet box manufacture, desirably low manufacturing costs for the cable clamp means have not been fully achieved. In some instances, it has been proposed to mold cable clamps integrally with plastic outlet boxes, but this has proved unsatisfactory to some degree, by reason of the expense involved in constructing the molds, and the difficulty of achieving high volume, trouble-free production runs of the device.
In other instances, it has been proposed to provide cable clamp attachments that are manufactured separately from the outlet boxes, and are thereafter attached thereto. These, however, have in many instances consumed an excessive amount of time in the attachment step. This is highly undesirable, because it adds to the cost of the installing electrician's labor. This is a fact which must clearly be reckoned with, especially in the installation of outlet boxes through, for example, an entire residential project in which profitable installation of the electrical systems is possible only if every possible step is taken to reduce labor costs.
The present invention, accordingly, aims to achieve several desirable purposes, notably the swift and easy, manual attachment of the cable clamp constituting the present invention, to an outlet or junction box; the efficient gripping of an inserted cable, responsive merely to the exertion of a force tending to pull the cable out of the box; and, very importantly, the adaptability for manufacturing the device at a minimum manufacturing cost, utilizing not only relatively inexpensive, high production molds, but also, extrusion processes for at least some of the forms of the invention.